This invention relates to a color reproduction apparatus, and more particularly to a high speed color reproduction apparatus.
Reproducing or copying color originals through a xerographic process has, in the past, entailed the sequential production of three color separation images of the colored original, with independent development thereof by cyan, magenta and yellow toners. The images so formed are transferred onto the copy substrate material in registered overlaying relationship, with the resulting composite color image being fused to provide a permanent full color reproduction of the original.
In the aforedescribed color process, black is obtained through an amalgam of the three color toners. However, it is often useful to provide a separate processing unit devoted solely to black. This addition enhances machine versatility since it is then possible to produce black and white copies directly and without the need to go through the color separation cycle. The addition of a separate black processing unit also enhances the quality and faithfulness of the black in color reproductions inasmuch as black is formed directly using black toner rather than a combination of multi-color toners.
However, while systems of the above type can provide full color reproductions, because of the need to process three and possibly four color separation images for each copy, the copy output is often very low. Where a single photoconductive drum is used for example, normally each color separation image is created, developed, and transferred to the copy substrate material before the next is started.
Where multiple photoreceptor processing units have been suggested to speed up copy output, it has often been at the expense of greatly increased machine physical size required to accommodate three and possibly four photoreceptor processing units. Attempts to alleviate this problem and reduce machine size through the use of different diameter photoreceptor drums or belts results in a system wherein a multiplicity of different size photoreceptor drums of belts must be stocked for replacement purposes, it being understood that photoreceptor drums and belts are subject to fatigue and damage and hence must be replaced from time to time.